The invention relates to a magnet system for a relay with the following characteristic features:
a core unit with at least two legs, whereby at least one armature bearing section is created on a first leg and a pole section is created on a second leg,
an armature, which is pivotally mounted on the armature bearing section around a bearing edge and preloaded by a spring force in an open position, whereby a working air gap is created between an armature pole face on a free armature end and a core pole face on the pole section, and
a coil, which surrounds the core unit at any chosen position.
Magnet systems for electromagnetic relays for the switching of direct current loads, as preferably used in motor vehicles, cause disturbing switching noises in the inside of the vehicle. In order to reduce these switching noises, which arise in particular from the impact of an armature on a pole face, it is for instance known to use a double-walled housing with sound absorbing features. This known measure is elaborate and expensive; it increases the volume of the relay and merely offers a sound absorbing or sound deadening effect, whereas the actual problem of the sound formation is not solved. In addition, the noise can be transferred outside via a connecting conductor. Furthermore, through the use of a double-walled housing, the heat conductivity of the housing is reduced whereby the operational capability of this type of relay is limited.
A solution for the avoidance of the noise formation consists in using a magnet system comprising a damper for the reduction of the speed of movement of the armature.
A relay is known from EP 0 281 384 B1, in which a noise reduction is achieved by reducing the speed of the armature. In this relay an additional air damper is coupled to the armature and the contact spring system. The disadvantage of this construction is that the relay becomes more expensive due to the damper and that in addition the space required increases.
It is the object of the invention to provide a magnet system of the above type which is simple in structure but nevertheless displays a low-noise switching behavior.
According to the invention, this object is achieved by a magnet system of the above type which is characterised in that the armature pole face in the region of its front end in the closing direction is essentially perpendicular to a connecting line towards the bearing edge and in that the core pole face extends at least substantially parallel to the armature pole face when the armature is attracted.
The arrangement according to the invention is advantageous in that the movement of the armature, directly before the closing position is reached, approaches the pole faces in a flattening angle, so that the pole faces of the armature and the core unit in the resting position of the closed state are parallel to each other.
A particularly simple structure is also obtained in that no additional parts are required to achieve a low-noise switching behavior.
The armature movement is preferably limited by a stop, which is positioned close to the bearing edge. In an advantageous embodiment, this is achieved in a particularly simple manner, in that the armature bearing section also forms the stop.
A particularly good noise reduction is achieved when the working air gap between the pole faces is not completely closed during the closing of the armature, i.e. so that a residual working air gap remains, whereby the armature pole face and the core pole face are parallel to each other.
Further details and embodiments are described in the dependent claims.